I really need help💔

So my boyfriend and I are long distance and he recently visited and we had sex. This was both our first times and we have both talked about how we haven’t done anything sexual with anyone else ever. After he left I started to not feel right down there I went to the urgent care and they told me I had a uti, a week later I went back cause I still didn’t feel good they told me it was a yeast infection from the medicine for the uti but they were still gonna run tests. Yesterday they called me and told me a have fucking clamydia. I called him and he is swearing up and down that he hasn’t done anything with anyone else and from what he is telling me I really want to believe him cause I don’t think he would do this but theirs doesn’t just happen by myself and he was the only one I was with. I don’t know what to do but my heart really hurts and I just want some advice:(